Containers such as metal cans, glass bottles, various plastic packages and the like have so far been known as packaging containers, and quality deterioration caused by oxygen contained in packaging containers has been a problem. Accordingly, it is tried in recent years as one of deoxidation packaging technologies to constitute containers from a multilayer material provided with an oxygen-absorbing layer comprising an oxygen-absorbing resin composition prepared by blending a thermoplastic resin with an iron base deoxidizer and the like to try to enhance a gas barriering property of the containers and develop packaging containers in which the containers themselves are provided with an oxygen-absorbing performance. For example, an oxygen-absorbing multilayer film is used as a film prepared by providing a conventional gas barriering multilayer film prepared by laminating a heat sealing layer and a gas-barriering layer with an oxygen-absorbing layer which is a thermoplastic resin layer dispersed therein with an oxygen absorbent via an intermediate layer comprising a thermoplastic resin in a certain case to endow the film with a performance of absorbing oxygen contained in a container as well as a performance of preventing oxygen from permeating from an outside, and it is produced by making use of production processes which have so far been publicly known, such as extrusion lamination, coextrusion lamination, dry lamination and the like (refer to a patent document 1).
On the other hand, resin compositions comprising polyamide, particularly xylylene group-containing polyamide as an oxidizable organic component and transition metal are known as compositions comprising polymers and having an oxygen-scavenging characteristic, and shown are the examples of resin compositions having an oxygen-scavenging performance and oxygen absorbents, packaging materials and multilayer laminated films for packaging which are obtained by molding the above resin compositions (refer to patent documents 2 to 8). Further, known as well are technologies in which the above oxygen-absorbing multilayer films are used for a cover material of a barriering container to tightly seal the barriering container to thereby prevent oxidative deterioration of a content thereof.
However, problems such as detection by a metal detector used for detecting foreign matters in foods and the like, deficiency of an inside visibility due to a problem of opacity and incapability of use thereof for beverages such as alcohols and the like which are damaged in a flavor by mixing of iron powder have been involved in compositions in which an oxygen absorbent such as iron powder and the like is used. Further, oxidation reaction of iron powder is used, and therefore an effect of absorbing oxygen can be exerted only on stored films having a high moisture.
On the other hand, in resin compositions which contain a transition metal catalyst and in which a polyamide resin is oxidized to exert an oxygen-absorbing performance, a xylylene group-containing polyamide resin is oxidized, and therefore involved therein is the problem that the resin is reduced in a strength due to oxidative deterioration to allow the packaging container itself to be reduced in a strength.
MXD6 which is polyamide obtained by polycondensation of metaxylylenediamine and adipic acid is shown as an example in which oxidation reaction is exerted by a polyamide resin and a transition metal catalyst. However, in a system in which MXD6 is mixed with transition metal, an oxygen-absorbing ability is so low in a certain case as to use it as an oxygen-absorbing resin composition to store well a stored film. Also, the viscosity is reduced due to oxidative decomposition of MXD6 in mixing with the transition metal, and a problem of a reduction in the processability has been involved therein. Further, in a system in which MXD6 is mixed with transition metal, a blend with a polyester resin such as polyethylene terephthalate (hereinafter shown as PET) and the like and a resin having a relatively high melting point such as nylon 6 and the like has so far been usually used.
Also, a fluid infusion container in which a liquid chemical is a content is used by connecting it directly with a tube and the like, and therefore it is handled in a state in which it is put in an exterior packing material comprising a synthetic resin film in order to prevent the container from being contaminated before actually used. A fluid infusion container is constituted from a resin which permeates oxygen in terms of a sanitation and the like, and therefore the exterior packing material has to have a gas barriering property in order to prevent a content fluid thereof from being changed in a quality by oxygen. However, oxygen is present more or less in an exterior packing material after tightly sealed, and the fluid content has to be prevented from being changed in a quality by oxygen which permeates as time passes even if a gas-barriering exterior packing material is used. Accordingly, a content fluid of a fluid infusion container has so far been prevented from being changed in a quality not only by charging an exterior packing material with the fluid infusion container at a low oxygen concentration but also by putting an oxygen absorbent together with the fluid infusion container in the exterior packing material to absorb remaining oxygen and permeating oxygen by the above oxygen absorbent to thereby maintain an amount of oxygen in the exterior packing material at a low level (refer to the patent document 1).
However, in resin compositions which contain a transition metal catalyst and in which a polyamide resin and the like are oxidized to exert an oxygen-absorbing performance, a xylylene group-containing polyamide resin is oxidized, and therefore involved therein is the problem that the resin is reduced in a strength due to oxidative deterioration to allow the packaging container itself to be reduced in a strength.